The softcover book is nothing but pages bound within a pliable paper cover like a paperback novel, or magazine. A softcover photo book feels more approachable, modern and friendly, and super affordable than the hard one. It makes people feel comfortable to grab in hand and carry too many places they want as it is weightless.
Hardcover photo book pages bound inside a cover made from thick, rigid paperboard. A hardcover, of course, protects the photo papers better and gives the book a luxurious feel and weight. The paper used in hardcover books is usually highly durable and made to last a long time, along with the cover. That's why a hardcover is rigid. Hardcover is intended to be rigid since such design is for making wedding albums lasting for many years.